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Abstract:

A radial shaft sealing ring for the sealing separation of an internal
space (6), from an external space (5), with a sealing lip (2) delimited
by a first and a second annular surface (3, 4) of a cone frustum,
wherein, the first annular surface (3) is oriented towards the external
space (5), and the second annular surface (4) is oriented towards the
internal space (6), wherein the annular surfaces (3, 4) are connected to
each other via a ring-shaped contact surface (23) of the sealing lip (2),
which rests on the shaft (7), wherein the first annular surface (3) forms
with the shaft (7) a first angle (β') of 23-40° in the
installed position, wherein an inner diameter (24) of the ring-shaped
contact surface (23) is 1-15 mm in the installed position.

Claims:

1. A sealing ring, particularly radial shaft sealing ring, for the
sealing separation of an internal space (6), which in each case at least
partially surrounds a shaft (7), from an external space (5), comprising:
a sealing lip (2) delimited by a first and a second annular surface (3,
4) of a cone frustum, wherein, in an axial direction (11), the first
annular surface (3) of a cone frustum is oriented towards the external
space (5), and the second annular surface (4) of a cone frustum is
oriented towards the internal space (6), wherein the annular surfaces (3,
4) of a cone frustum, in the installed position, are connected to each
other via a ring-shaped contact surface (23) of the sealing lip (2),
which rests on the shaft (7), wherein the first annular surface (3) of a
cone frustum forms with the shaft (7) a first angle (β') of
23-40.degree. in the installed position, wherein an inner diameter (24)
of the ring-shaped contact surface (23), which rests on the shaft (7), is
1-15 mm in the installed position, as a function of the diameter of the
given shaft (7) to be sealed off.

2. The sealing ring according to claim 1, wherein the first angle
(β') is 28-35.degree. in the installed position.

3. The sealing ring according to claim 1, wherein the second annular
surface (4) of a cone frustum forms with the shaft (7) a second angle
(α') of 37-57.degree. in the installed position.

4. The sealing ring according to claim 1, wherein the first angle
(β) is 37-50.degree. in the uninstalled state.

5. The sealing ring according to claim 3, wherein the second angle
(α) is 30-45.degree. in the uninstalled state.

9. The sealing ring according to claim 1, wherein the sealing ring (1)
includes a hollow cylindrical section (16), to which the sealing lip (2)
is attached in such a manner that an inner lateral surface (17) of the
hollow cylindrical section (16) transitions into the first cylindrical
surface (3) of a cone frustum.

10. The sealing ring according to claim 1, wherein the first cylindrical
surface (3) of a cone frustum is designed without kinks.

12. The sealing ring according to claim 1, wherein on the side of the
sealing lip (2), which is radially turned away, a ring-shaped clamping
element (20) is arranged, by means of which the sealing lip (2) can be
pressed on the shaft (7) in the installed position.

13. The sealing ring according to claim 12, wherein a working plane (21)
of a radial force action of the clamping element (20) is moved with
respect to a contact plane (22) of the sealing lip (2) axially in the
direction of the external space (5).

Description:

[0001] This application claims the benefit and priority of European Patent
Application No. 10 015 718.9-1252, filed Dec. 16, 2010. The entire
disclosure of the above application is incorporated herein by reference.

FIELD

[0002] The present disclosure relates to the sealing of housing openings
through which a shaft passes, by means of sealing rings, wherein the
sealing rings separate an internal space, which in each case at least
partially surrounds the shaft, from an external space. Here, the internal
space can be a housing internal space which is separated, optionally in a
pressure-tight manner, by a sealing ring with respect to an external
space surrounding the housing, so that fluids, gases and/or aerosols
cannot exit from the housing internal space, and no introduction of
material from the external space into the housing internal space can
occur. Accordingly, the disclosure also relates to a housing having such
a sealing ring.

BACKGROUND

[0003] In EP 1 156 242 B1, a sealing ring is disclosed, which is designed
as a radial shaft sealing ring, and which is constructed from a
ring-shaped metal supporting body and a sealing lip attached to it. The
radial shaft sealing ring, in the installed position, has a shaft passing
through it, where the sealing lip separates in a sealing manner a
hydraulic side, particularly one that is under pressure, or an internal
space or a housing internal space, from an atmospheric side or an
external space. Moreover, the sealing lip is pressed by means of an
annular helical spring on the shaft, and in addition, an additional
sealing lip, oriented towards the atmospheric side, can further reduce
the introduction of soiling material in the direction of the hydraulic
side, and thus in the direction of the housing internal space. The
sealing lip is formed substantially by two cylindrical surfaces of a cone
frustum, where the first cylindrical surface of a cone frustum is
oriented towards the atmospheric side or towards the external space, and
the second cylindrical surface of a cone frustum is oriented towards the
hydraulic side or the internal space. The first cylindrical surface of a
cone frustum presents a kink, so that, in the uninstalled state of the
sealing ring, an angle α of 35-65°, preferably 45-60°
can be formed between the axial direction and the first cylindrical
surface of a cone frustum, in the area of the contact surface of the
sealing lip on the shaft. The angle β of the second cylindrical
surface of a cone frustum with respect to the axial direction in the
uninstalled state is 15-30°, preferably 17-22°. In the
installed position of the sealing ring with the shaft, the angles α
and β are approximately of equal size, and then have values between
20 and 50°, preferably 30°. This change of the angles
α, β of the uninstalled state compared to the installed
position is explained by an overlap, due to which, when the shaft is
introduced into the sealing ring, on the one hand, precisely this change
in angle occurs, and, on the other hand, the periphery of the sealing lip
at the time of the installation of the shaft is elastically broadened.

[0004] In DE 24 58 773 A1, a seal is described, particularly for rotary
shafts, which consists of a metal ring-shaped supporting body, to which a
sealing lip is attached. To prevent buckling due to a pressure load
caused by the pressure in the housing internal space, the surface which
is oriented towards the external space and forms the sealing lip is
designed so it is free of kinks. In addition, any discontinuities of
precisely this surface, which delimits the sealing lip, and which is
oriented towards the external space, would potentially lead to a folding
over or folding down of the sealing lip, in the installation of the
shaft. This effect can be decreased or prevented by a design without kink
or a design without discontinuity. Here, the angle between this surface
delimiting the sealing lip in the area of the contact surface of the
sealing lip on the shaft--before the installation of the shaft--is at
least 35°. Due to the overlap, this angle may end up being smaller
in the installed position of the seal with the shaft. In addition, due to
a potential relative excess pressure generated in the housing internal
space, the value of this angle can be further decreased.

[0005] Sealing rings whose sealing lips are delimited by mutually
intersecting tapered surfaces, that is cylindrical surfaces of a cone
frustum, are thus usually used as seals in the area of housing openings,
in which a shaft passes through the housing. Usually, the lip of the
sealing ring, with respect to the surface to be sealed off or with
respect to the shaft to be inserted in the sealing ring, presents a
radial overlap, so that when the shaft is inserted into the sealing ring,
the sealing lip is under radial preliminary tension and broadened. Due to
the radial preliminary tension, the sealing lip encloses the surface or
shaft to be sealed off in a sealing manner. In the case of large inner
diameters >20 mm of the forming ring-shaped contact surface of the
sealing lip on the shaft, the preset overlap of the sealing lip towards
the shaft surface to be sealed off has nearly no effect on the axial
width of the contact surface. This is due to the fact that sealing rings
with large diameters and associated large sealing lip peripheral lengths,
at the time of their installation on the shaft, can be broadened without
problem by the amount of the overlap, without disadvantageous effect on
the radial contact pressure of the sealing lip on the surface to be
sealed off, and thus on the axial width of the contact surface. However,
the smaller the shaft diameter, and thus also the inner diameter of the
ring-shaped contact surfaces of the sealing rings, becomes, the smaller
the resulting possible expansion of the sealing lip over the periphery
is. Accordingly, with decreasing shaft radius or inner diameter of the
contact surface of the sealing lip on the shaft, a broadening of
precisely this contact surface can occur due to an undesired large
deformation and contact pressure of the sealing lip on the surface to be
sealed off. However, a broadening of the contact surface causes greater
wear of the sealing lip as well as a worsened, undifferentiated sealing
behavior. If, in addition, the contact surface is shifted more strongly
towards the external space or towards the atmospheric side, particularly
during start-stop operation, nicking or notching in the sealing lip
occurs increasingly, particularly in the case of insufficient
lubrication. As a result, leaks can develop in the area of the sealing
lip.

SUMMARY

[0006] The present disclosure is based on the problem of providing an
improved sealing ring or an improved housing with such a sealing ring,
wherein the sealing ring should present good performance characteristics
for a long service life, even if it has only a small diameter.

[0007] As an aspect of the present disclosure, a sealing ring is proposed,
particularly a radial shaft sealing ring for the sealing separation of an
internal space, which at least partially surrounds the shaft, from an
external space which also surrounds the shaft at least partially. Said
sealing ring is provided with a sealing lip delimited by a first and a
second annular surface of a cone frustum. Here, the first annular surface
of a cone frustum is oriented in the axial direction towards the external
space, while the second annular surface of a cone frustum is oriented in
the axial direction towards the internal space. Moreover, the annular
surfaces of a cone frustum, in the installed position, are attached to
each other via a ring-shaped contact surface of the sealing lip, which
rests on the shaft. The first annular surface of a cone frustum together
with the shaft in the installed position forms a first angle of
23-40°. The inner diameter of the ring-shaped contact surface
resting on the shaft here is 1-15 mm, in the installed position, as a
function of the diameter of the given shaft to be sealed off.

[0008] Advantageously, by means of such a design of the sealing lip, in
spite of the overlap of the surface to be sealed off, a small axial width
of the contact surface can be formed in the installed position with the
shaft.

[0009] A shaft can be arranged which passes through a housing or a housing
opening in such a manner that the shaft is surrounded both by the housing
internal space and also by the external space surrounding the housing. In
the housing opening through which the shaft passes, a sealing ring can be
inserted for the sealing or separation of the internal space with respect
to the external space, in accordance with the intended purpose. The
housing internal space here can contain fluids, gases, aerosols or the
like, and it can be under increased pressure compared to the external
space. Accordingly, the sealing ring prevents the exit of the fluids,
gases, aerosols or the like contained in the housing internal space.
Moreover, the sealing ring prevents the introduction of material from the
external space into the internal space. As a result, soiling of the
internal space and the fluids, gases, aerosols or the like contained
therein, with soiling material originating from the external space, can
be prevented advantageously.

[0010] The sealing lip of the sealing ring, which, in the installed
position with the shaft, substantially achieves the separation of the
external space from the internal space, is delimited by two annular
surfaces of a cone frustum. In other words, the sealing lip is delimited
by mutually intersecting conical lateral surfaces. In the uninstalled
state and possibly without wear traces, the cylindrical surfaces of a
cone frustum of the sealing lip can be connected to each other via a
circular contact edge. When the shaft is then introduced, the sealing
ring is converted into the installed position, and due to an overlap, the
sealing lip is pressed on the shaft in such a manner that a ring-shaped
contact surface is formed on the sealing lip, by means of which the
sealing lip then rests on the shaft. Here, overlap or a radial overlap
denotes a difference between the shaft radius and the relatively smaller
radius of the sealing lip in the uninstalled state. If the shaft is now
introduced into the sealing ring, then the sealing lip is broadened in
the peripheral direction precisely due to said overlap, and the
ring-shaped contact surface is formed, by means of which the sealing lip
rests on the shaft. Here, in the uninstalled state, the sealing lip can
also have a round design, between the two annular surfaces of a cone
frustum. The axial direction denotes the direction along the shaft in the
installed position with the sealing ring.

[0011] The inner diameter of the ring-shaped contact surface applied on
the shaft, and thus the shaft diameter, can be 3-15 mm in the installed
position.

[0012] It is precisely with such small inner diameters or shaft diameters
that, using the above indicated embodiments of the sealing ring, which
are described below, the desired small axial width of the contact surface
can be formed. As a result, particularly for said small shaft diameter or
inner diameter, a greater robustness of the sealing ring can be ensured.
In addition, nicking or cracking in the sealing lip can at least be
decreased, particularly in case of insufficient lubrication, especially
during start-stop operation. In addition, the sealing ring, particularly
with regard to its sealing effect, is less sensitive especially to a
possible shaft eccentricity or with regard to pressure.

[0013] Such a centralized arrangement of the contact surface, in which the
portions of the contact surfaces which face the external space and the
internal space are designed in a balanced manner or with nearly identical
size, can be achieved by a first angle of 23-40° in the installed
position. Moreover, the design of the contact surface can be improved by
a first angle of 28-35°.

[0014] This design of the contact surface can be supported by a
corresponding design of a second angle, which is arranged between the
second annular surface of a cone frustum and the shaft in the installed
position. This second angle can be 37-57°, preferably
42-52°. Due to such a design of the second angle, the width of the
contact surface can also be minimized, and the portions of the contact
surface in the external space and internal space can be designed in a
balanced manner.

[0015] Such advantageous first and second angles in the installed position
of the sealing ring with the shaft can be designed in a supporting manner
during the installation by the fact that the first and the second angle
present a corresponding preset value in the uninstalled state.

[0016] Thus, the first angle in the uninstalled state can present a value
of 37-50°, preferably 42-45°. The second angle in the
uninstalled state can present a value of 30-45°, and preferably
35-40°.

[0017] With such preset first and second angles in the uninstalled state
of the sealing ring, the advantageous first and second angles in the
installed position of the sealing ring with the shaft can be represented,
after the installation of the shaft in the sealing ring.

[0018] In addition, the sealing ring can present an additional sealing lip
arranged in the external space and/or oriented towards the external
space. This additional sealing lip can advantageously further decrease or
prevent the introduction of material from the external space into the
internal space, and thus counteract the soiling of the internal space.

[0019] Moreover, an intermediate space can be provided between the sealing
lip and the additional sealing lip. Said intermediate space is delimited
by the sealing lips, and sealed off by the two sealing lips. In the
installed position with the shaft, a lubricant can be introduced, for
example, fat, oil, graphite, Teflon or the like, in said intermediate
space. In this manner, the intermediate space arranged between the two
sealing lips can advantageously serve as a lubricant reservoir.

[0020] Moreover, the sealing ring can present a ring-shaped, bearing
supporting body. This ring-shaped bearing supporting body can be
manufactured from metal or from another heat resistant and deformation
resistant material. This ring-shaped, bearing supporting body can be
designed advantageously as a sleeve.

[0021] By means of this ring-shaped, bearing supporting body, the sealing
ring can be stabilized and stiffened overall. As a result, the ease of
handling is simplified, particularly at the time of the installation. In
addition, due to the ring-shaped, bearing supporting body, the outer
shape and dimension of the sealing ring are substantially predetermined.
The sealing ring can be installed so it is held permanently in its
installation space in a housing.

[0022] Moreover, the sealing ring can present a hollow cylindrical section
to which the sealing lip is attached in such a manner that an inner
lateral surface of the hollow cylindrical section transitions into the
first annular surface of a cone frustum.

[0023] The first annular surface of a cone frustum, which transitions
directly into the inner lateral surface of the hollow cylindrical
section, can be designed so it is free of kinks. Due to the absence of
discontinuities or kinks in the first annular surface of a cone frustum,
a flapping over or buckling over of the sealing lip at the time of the
installation of the shaft in the sealing ring can be avoided or
prevented.

[0024] Moreover, the ring-shaped bearing supporting body can be connected
via a hollow cylindrical section to the additional sealing lip.
Accordingly, the intermediate space arranged between the two sealing lips
can be designed by means of the hollow cylindrical section in such a
manner that a corresponding desired volume can be optimized, for example,
for a lubricant reservoir.

[0025] Moreover, on the radially turned away side of the sealing lip, a
ring-shaped clamping element can be arranged, by means of which the
sealing lip can be pressed on the shaft in the installed position.

[0026] Such a clamping element can be designed as an annular helical
spring. The clamping element presents a radial force action. The clamping
element can be designed as a separate component made of metal, for
example, or it can be molded integrally with the sealing lip from an
elastic material. In this manner, it is also conceivable that the
clamping element is formed from the same or from a similar material as
the sealing lip, integrally with the latter.

[0027] Advantageously, an additional contact pressure can be generated by
the clamping element, by means of which the contact surface can be
shaped, in addition to the other possible forces. Thus, for example, by
changing the working plane of the radial force action of the clamping
element, a change in the position as well as the shape of the contact
surface is possible.

[0028] Here, the working plane of the radial force action of the clamping
element can be shifted with respect to a contact plane of the sealing lip
axially in the direction of the external space. This can be the case in
the installed position and/or in the uninstalled state of the sealing
ring. By means of such a positioning of the clamping element, a greater
robustness, particularly with respect to the eccentricity of the shaft
and a corresponding pressure application from the internal space, can be
achieved. The angles of the annular surfaces of a cone frustum relative
to the surface to be sealed off are as a result equally stable throughout
the entire service life of the sealing ring.

[0029] The sealing lip as well as the additional sealing lip and also the
hollow cylindrical section can be made of the same material or of
different materials. All the above-indicated components can be formed
from a material having the same or a different elasticity. The
above-mentioned components can be formed in any combination from the same
material or a different material as well as from a material having the
same elasticity or a different elasticity. The above-mentioned components
can be designed in a different combination with respect to each other
integrally or in multiple parts. Thus, they can be attached by molding to
each other using different or identical materials, or they can present an
additional supporting body for stabilization, to which an elastic
material is applied by molding. The hollow cylindrical section can be
attached by molding to the ring-shaped, bearing supporting body, or
connected by another means to the same.

[0030] In an additional aspect of the invention, a housing with a sealing
ring as described above is proposed. Such a housing presents a more
robust and less sensitive sealing with less wear during operation, even
if the sealing ring which is used, during its use for its intended
purpose, in adaptation to the shaft diameter to be sealed off, presents
an inner diameter of only 3-15 mm.

DRAWINGS

[0031] The figures each show diagrammatically:

[0032] FIG. 1 is a sealing ring in the uninstalled state, and

[0033]FIG. 2 is the sealing ring in the installed position with a shaft.

DETAILED DESCRIPTION

[0034] FIG. 1 represents a sealing ring 1 in the uninstalled state. Said
sealing ring 1 is provided with a sealing lip 2 which is delimited by a
first annular surface 3 of a cone frustum and a second annular surface 4
of a cone frustum. The first annular surface 3 of a cone frustum is
oriented towards an external space 5, and the second annular surface 4 of
a cone frustum is oriented towards an internal space 6. Because such a
sealing ring 1 can be used to seal off, for example, a shaft 7 which
passes through a housing opening, the internal space 6 can represent a
housing internal space, while the external space 5 surrounds the housing.

[0035] In the represented uninstalled state, the shaft 7 to be introduced
later is also represented, to illustrate an overlap 9 of the sealing lip
2. Between the first annular surface 3 of a cone frustum and the shaft 7
to be introduced subsequently, a first angle β is arranged, and a
second angle α is arranged between the second annular surface 4 of
a cone frustum and the shaft 7 to be introduced subsequently.

[0036] Moreover, the sealing ring 1 is provided with an additional sealing
lip 10 which is oriented in the axial direction 11 towards the external
space 5. Between the two sealing lips 2, 10, an intermediate space 12 is
arranged. By means of the two sealing lips 2, 10, the intermediate space
12 is closed off in a sealing manner with respect to the external space 5
and/or with respect to the internal space 6.

[0037] The sealing ring 1 is also provided with a ring-shaped, bearing
supporting body 13 which serves to stabilize, stiffen, and form the outer
shape of the sealing ring 1. Due to the complementary formation of the
outer shape of the sealing ring 1, it becomes possible to introduce the
sealing ring 1 in a simple manner into the housing opening 14 of the
housing 15. Moreover, the sealing ring 1 presents a hollow cylindrical
section 16, to which the sealing lip 2 is connected in such a manner that
an inner lateral surface 17 of the hollow cylindrical section 16
transitions without abrupt changes in direction into the first annular
surface 3 of a cone frustum. The first annular surface 3 of a cone
frustum, which extends from the attachment place 18 of the inner lateral
surface 17 to the first annular surface 3 of a cone frustum up to the
contact edge 8, is designed without kinks.

[0038] The hollow cylindrical section 16 is attached to the ring-shaped,
bearing supporting body 13, and connected to the additional sealing lip
10 as well as the sealing lip 2. In addition, the sealing ring 1
presents, on the side turned radially away from the sealing lip 2, a
ring-shaped clamping element 20, by means of which the sealing lip 2 is
pressed on the shaft 7 in the installed position. Here, a working plane
21 of a radial force action of the clamping element 20 is moved with
respect to a contact plane 22 spanned by the circular contact edge 8, in
the axial direction 11 towards the external space 5.

[0039] In FIG. 1, the additional parameters PD, s, sh, e of the
sealing lip 1 in the uninstalled state are also indicated; they are
further specified in the following embodiment example.

EMBODIMENT EXAMPLE

[0040] Variation of the measurements of a possible embodiment as shown in
FIG. 1

[0041] In the embodiment shown in FIG. 1, all the combinations of the
above-indicated values for the parameters are admissible and usable.

[0042]FIG. 2 represents the sealing ring 1 of FIG. 1 in the installed
position with the shaft 7. Here, in the installed position, the first
angle β' and the second angle α' is another angle than the
first angle β and the second angle α in the uninstalled state.
In addition, a contact surface 23 forms at the time of the installation
of the shaft 7.

[0043] In the installed position, the inner diameter 24 of the contact
surface 23 corresponds to the diameter to be sealed off of the shaft 7.
Similarly, the working plane 21, in the installed position, assumes
another position with respect to the contact plane 22 than in the
uninstalled state.